You most likely did not actually install X11 or anything like that, however, you probably have lots of GTK+ libs and other related junk on your system. If you change your mind, you can execute the following commands to remove Gedit and its depedencies, without breaking anything else:

sudo apt-get remove gedit
sudo apt-get autoremove

This will remove any packages which apt-get installed automatically and which are no longer needed.

If you want to use something better than nano, try using sftp to download the file, edit it in your editor of choice, and then upload it again. If you have OpenSSH as the SSH server this may be available without reconfiguring anything or installing additional software.